The present invention relates to a vehicle positioning system in which the position of the vehicle on a road is determined by detecting electromagnetic lane markers laid under the road with an electromagnetic lane marker detector installed on the vehicle.
Information about road conditions including lanes and curves has been provided by such lane marks as white lines and traffic signs, and drivers check them visually.
However, when visibility is low at night or as a result of weather conditions, it is difficult for drivers to correctly obtain information of the road visually, thus safety on the road can be threatened. To prevent road hazards, magnetic nails have been tried to provide road information to drivers. However, when trying to enhance detectivity of these magnetic nails by making them ferromagnetic, they tend to attract metallic pieces left on the road. This increases the risk of puncture, a problem which does not coincide with increasing performance. As such, problems regarding the magnetic nail have not yet been solved.
Electrical resonators have been sometimes used as an anti-theft device. In this field, an electrical resonator is mounted on a film and attached to a product so that a device that can detect the electrical resonator, installed at the entrance of the shop, can detect to it. The electrical resonators have also been applied to the non-contacting card system where information recorded on IC mounted on an electrical resonator is read out.
However, the level of the electromagnetic waves emitted by a resonance of the electric resonator is very weak compared with the level of calling electromagnetic waves transmitted by a detector; normally it is only about one millionth of that of the calling waves. When an IC is mounted on an electric resonator, and a modulated information code is superposed, the level of the superposed electromagnetic waves further declines. Consequently, when transmitting and receiving the electromagnetic waves of the same frequencies, interference of the calling waves becomes unavoidable, thereby obstructing achievement of sufficient directivity and detection distance.
A first electromagnetic lane marker of the present invention include an electric resonator comprising a cyclic coil and a capacitor, which resonates with inductive electromagnetic wave of a first frequency. The electromagnetic lane marker further includes a frequency conversion circuit coupled to the electromagnetic resonator, and transmits electromagnetic waves of a second frequency which was converted from the resonated first frequency.
A second electromagnetic lane marker of the present invention include an electronic resonator comprising a first cyclic coil and a capacitor, which resonates with inductive electromagnetic wave of a first frequency, a frequency conversion circuit coupled to the electronic resonator, which converts the electromagnetic wave of the first frequency to electromagnetic wave of a second frequency, and a second cyclic coil which transmits the electromagnetic wave of the second frequency.
A third electromagnetic lane marker of the present invention include
an electronic resonator comprising a first cyclic coil and capacitors connected to both ends of the first cyclic coil, which resonates with inductive electromagnetic wave of a first frequency, a frequency conversion circuit coupled to said electronic resonator, which converts the electromagnetic wave of the first frequency to electromagnetic wave of a second frequency, and a second cyclic coil which transmits the electromagnetic wave of the second frequency. And, the electric resonator, the frequency conversion circuit and the second cyclic coil are stored in a sealing container made of a non-magnetic material.
In a fourth electromagnetic lane marker, the sealing container of the third lane marker is cylindrical with a bottom base and a lid.
A fifth electromagnetic lane marker is constructed based on the second through fourth lane markers, in which the first and second cyclic coils are formed respectively with a loop antenna and a bar antenna.
A sixth electromagnetic lane marker is constructed based on the second through fourth lane markers, in which the first and second cyclic coils are formed respectively with a bar antenna and a loop antenna.
A seventh electromagnetic lane marker is constructed based on the second lane marker, in which the first and second cyclic coils are disposed at right angles.
An eighth electromagnetic lane marker is constructed based on the first through seventh lane markers, in which the frequency conversion circuit is a frequency multiplier circuit which converts the second frequency to the frequency of multiples times of the first frequency.
A ninth electromagnetic lane marker is constructed based on the second through eighth lane markers, in which an xe2x80x9cL-tap structurexe2x80x9d is adopted for the second cyclic coil.
A tenth electromagnetic lane marker is constructed based on the first through eighth lane markers, in which a xe2x80x9cC-tap structurexe2x80x9d is adopted for the second cyclic coil.
An eleventh electromagnetic lane marker is constructed based on the first through tenth lane markers, in which the frequency conversion circuit is formed with a parallel rectifier structure.
A twelfth electromagnetic lane marker is constructed based on the first through tenth lane markers, in which the frequency conversion circuit is formed with a diode bridge.
A first electromagnetic lane marker detector of the present invention includes a means for transmitting electromagnetic waves of a specific frequency as the first frequency wave, and identifying and receiving electromagnetic waves of the second frequency converted from the first frequency and transmitted by the frequency conversion circuit coupled to the electrical resonator mounted on the electromagnetic lane marker.
A second electromagnetic lane marker detector of the present invention is constructed based on the first electromagnetic lane marker detector, in which a loop antenna is used to transmit the electromagnetic waves of the first frequency, and a bar antenna to receive the electromagnetic waves of the second frequency.
A third electromagnetic lane marker detector of the present invention is constructed based on the first and second electromagnetic lane marker detectors, in which a 8-letter shaped loop antenna is used to transmit the electromagnetic waves of the specific first frequency.
A third electromagnetic lane marker detector of the present invention constructed based on the first to third electromagnetic lane marker detectors includes a plurality of receiving antennas to receive electromagnetic waves of the specific second frequency and a position detector which maps, out the relative positions of the lane marker and the receiving antennas by comparing the intensity of the electromagnetic waves received by the antennas.
A fourth electromagnetic lane marker detector of the present invention constructed based on the first through fourth electromagnetic lane marker detectors, includes a means for monitoring the amount of lateral deviation of the vehicle from the markers and an alarm which alerts a driver when the vehicle exceeds a predetermined threshold.
A fifth electromagnetic lane marker detector of the present invention constructed based on the fourth electromagnetic lane marker detector, contains a means for changing the reference deviation in terms of the threshold distance from the lane marker, which is used as a reference to alert the driver.
A sixth electromagnetic lane marker detector of the present invention constructed based on the fourth and fifth electromagnetic lane marker detectors, includes an alarm comprising one of a visible alarm, an audible alarm such as a buzzer or a voice notification, and a vibration.
A seventh electromagnetic lane marker detector of the present invention constructed based on the fourth and fifth electromagnetic lane marker detectors, includes a lateral-deviation-sensitive alarm which changes the contents of the alerting according to the amount of the lateral deviation.
An eighth electromagnetic lane marker detector of the present invention constructed based on the first through seventh electromagnetic lane marker detectors, includes a transmitting means which is capable of detecting a speed of the vehicle, and when the speed is below a predetermined level, it stops transmitting the electromagnetic waves of the first frequency, and when above, it resumes transmission.
A ninth electromagnetic lane marker detector of the present invention constructed based on the first through eighth electromagnetic lane marker detectors, has a height-specific transmitting power controlling means which is capable of controlling the transmitting amplifiers such that the transmitting power changes according to a setting height of the vehicle.
A tenth electromagnetic lane marker detector of the present invention constructed based on the first through ninth electromagnetic lane marker detectors, has a height-sensitive transmitting power controlling means which is capable of detecting the height of the vehicle and controls the transmitting amplifiers such that the transmitting power changes according to the detected height of the vehicle.
A first vehicle positioning system of the present invention comprises the following elements:
1) an electromagnetic lane marker comprising the following elements:
a) an electric resonator comprising a cyclic coil and a capacitor, which resonates with induction electromagnetic waves of a first frequency;
b) a frequency conversion circuit coupled to the electric resonator, which converts the first frequency and transmits the electromagnetic waves of the second frequency
2) an identifying and receiving means for receiving the second electromagnetic frequency which is converted from the first frequency transmitted as a specific electromagnetic frequency and transmitted by the frequency conversion circuit coupled to the electrical resonator mounted in the electromagnetic lane marker.
In a second vehicle positioning system of the present invention which is based on the first vehicle positioning system, the electromagnetic lane markers are laid under the road.
According to a third vehicle positioning system, based on the second vehicle positioning system, electromagnetic lane markers laid at predetermined intervals support automatic driving.